The residents of a rural mining town discover that an unfortunate chemical spill has caused hundreds of little spiders to mutate overnight to the size of SUVs. It's then up to mining engineer Chris McCormack and Sheriff Sam Parker to mobilize an eclectic group of townspeople, including the Sheriff's young son, Mike, her daughter, Ashley, and paranoid radio announcer Harlan, into battle against the bloodthirsty eight-legged beasts. Venomous spiders get exposed to a noxious chemical that causes them to grow to monumental proportions.